Update README.md

added some packages which I needed to install manually and a typo

Author: Nuri-benbarka

README.md

@@ -11,6 +11,8 @@ Our model is trained and tested under:
 * sklearn
 * numba
 * cffi
+* pypng
+* pptk
 
 Compile the furthest point sampling, grouping and gathering operation for PyTorch. We use the operation from this [repo](https://github.com/sshaoshuai/Pointnet2.PyTorch).
 
@@ -22,7 +24,7 @@ cd ../
 
 ## Data preprocess
 
-For fair comparison with previous methods, we adopt the preprocessing steps in [HPLFlowNet](https://web.cs.ucdavis.edu/~yjlee/projects/cvpr2019-HPLFlowNet.pdf). Please refer to [repo](https://github.com/laoreja/HPLFlowNet). We alos copy the preprocessing instructions here for your reference.
+For fair comparison with previous methods, we adopt the preprocessing steps in [HPLFlowNet](https://web.cs.ucdavis.edu/~yjlee/projects/cvpr2019-HPLFlowNet.pdf). Please refer to [repo](https://github.com/laoreja/HPLFlowNet). We also copy the preprocessing instructions here for your reference.
 
 * FlyingThings3D:
 Download and unzip the "Disparity", "Disparity Occlusions", "Disparity change", "Optical flow", "Flow Occlusions" for DispNet/FlowNet2.0 dataset subsets from the [FlyingThings3D website](https://lmb.informatik.uni-freiburg.de/resources/datasets/SceneFlowDatasets.en.html) (we used the paths from [this file](https://lmb.informatik.uni-freiburg.de/data/FlyingThings3D_subset/FlyingThings3D_subset_all_download_paths.txt), now they added torrent downloads)